People I normally respect have bought in on some crazy-ass conspiracy theories.  Elon, Balaji, PMarca... all super smart, and all tweeting crazy shit. I did some research to see why people get hooked on conspiracy theories:
https://www.charterless.com/p/do-your-own-research-the-psychology

Writing about DAOs @ charterless.com.
Ex-FB, Amherst College.
Always an Eagles Fan.

It is a great thing about American culture. Following research is good and useful, as is critical thinking.  

CTs are when those are perverted through misleading a reader to appeal to their existing biases to provoke violence/hatred.

Per my reply to Dan, I find this a useful heuristic: https://i.imgur.com/oJiMZQ7.png

questioning authority is a great thing about American culture, it doesn't make Americans conspiracy theorists. 

if anything people aren’t questioning msm narratives enough, that’s the more “terrifying”

sure, 
- Balaji on SBF's delayed-arrest (it must be because he donated money and not because a massive financial fraud case takes longer than 24 hours to generate a winning case for...).
- Marc Andreesen on WEF paranoia. And claiming that there was some kind of mainstream alliance in favor of Ehrlich's pop bomb theory.

Examples of crazy conspiracy theories (minus Elon)?